A first kind of conventional fragrant oil volatilizing device is a multi-functional wall electric vaporizer, as disclosed in a Taiwan patent No. 568747 (European Patent Alliance 81, No. 01830528.4, Applicants: S.C.JOHNSON & SON, INC.). Such a wall electric vaporizer is provided with a container for receiving therein a bottle with liquid and a wick, and an electric heater for heating the wick of the bottle to volatilize the liquid in the bottle.
A second kind of conventional fragrant oil volatilizing device is a bactericide and fragrant oil volatilizing device installed inside an automobile, as disclosed in a Taiwan patent No. 240223. Such a device is provided with a power socket to be fixed inside an automobile and a negative ion producer on an electronic base board for carrying out sterilization. The electronic base board is provided with a heater received in a secondary chamber for heating and evaporating the fragrant oil in the secondary chamber.
A third kind of conventional fragrant oil volatilizing device is a whirlwind-typed vapor negative ion fragrance producing device, as disclosed in a Taiwan patent No. 564751. This device is provided with a rotary disk driven to rotate by a motor and having a plurality of arc-shaped blades spaced apart to make up an air current producer that can be driven to produce high-speed air current for stirring up the liquid in a container to produce negative ion.
A fourth kind of conventional fragrant oil volatilizing device is a drug or fragrant oil or essential oil vaporizer, as disclosed in a Taiwan patent No. 547087. This vaporizer is provided with a supersonic oscillator at the bottom of a container for evaporating the drug or the fragrant oil or the essential oil in the container.
The above-mentioned four kinds of conventional fragrant oil volatilizing devices carry out volatilization of fragrant oil either by electric heating or by high-speed rotation of the blades of the air current producer or by vibration of the supersonic oscillator, but none of these devices makes use of negative ion to directly volatilize essential oil; nor is the marked effect of the negative ion mentioned in these devices.